Sputtering 450r - Help

[Micheal Smith]

I have recently purchased the above quad. It still has the dimples on the tires and appeared brand new. I looked underneath the bike and it looks as new. The gentleman that I bought from said the bike only had 7-8 hours tops because he got into an auto accident and could not walk for several months.

My problem is that it seems to sputter a lot. When I rode it the first day I thought that it was just cold and needed to warm up. Yesterday it was doing the same after letting it warm up for 15 minutes and taking it on a 25-minute ride. It seemed to want to stall when jabbing the gas. I was wondering if you all had any information that I may try to help the issue. The bike did sit up for a while and was not started for several months. It starts right up with no problems though. I thought of the following:

1. Change spark plug
2. Drain gas and refill with new
3. Inspect for trash in the carburetor
4. Change oil & filter (as a precaution not a solution to the sputtering)

Any help would be greatly appreciated.

Thanks,
Georgian

[ISurvivedNMU]

Well, the spark plug is most likely not it, but its cheap to change.

Oil and filter... probably not it, but well worth changing....

FUEL..... Pending how long the bike sat... you need to run it out, or drain it. These bikes need premium fuel. As gas sits, it loses octane, and also can gum up.

I had the same issue with a bike that I bought that sat for 4 months. I drained the fuel, then drained the carb bowl and blew out the carb. Everything looked OK, and with the new fuel, it starts and idles much better.

15 minute warm up is excessive. You will most likely foul the plug after a few times of that. In the cold, I let it go with the choke on for about 2 minutes and drive it slow for a few minutes, and call that good.

[sinzbrosracing4]

does it have an aftermarket exhaust on it? if so the guy probably didnt re jet it.

[Micheal Smith]

bone stock

[GPracer2500]

what year?

[Micheal Smith]

06 electric start version

[ISurvivedNMU]

How is the idle speed.... If the idle is too low, I know they will sputter.. and die...

Do you have a atv tach?

[Micheal Smith]

Idle speed is fine. It will sit an idle fine when warmed up. The sputtering only occurs when jabbing the throttle, it is fine when the throttle is slowly pushed in. I do not have a tach.

Thanks for any advise.

Micheal Smith

[ISurvivedNMU]

My Bad...

Here is your answer

read it all

http://www.exriders.com/vbb/showthread.php?s=&threadid=286516

change the leak jet. the come way too big from the factory. it has a stock size 70 in it...go down to at least 42...

look at this diagram...http://www.sudco.com/fcrmx.html
the leak jst is number 29(numbered, but not listed). it screws into number 47 where number 52 is at...29 is in about the middle of the diagram and 47 and 52 is towards the bottom left

this will eliminate that bog you get when you jab the throttle real fast...

this hjet controls how much and how fast the fuel goes from the acc pump into the carb itself. a bigger number jet allows lets the fuel get in faster, or too fast... then it gets burned too fast and there is a short period where there is too little fuel...that is when you get the sputter...if you slowly roll on the throttle, the fuel does not get shot into the chamber as fast...i hope you can understand what i am saying...my brain aint firing on all 8 cylinders right now...i just woke up from only 4 hours of sleep